1. Field of the Invention
This invention relates to a board-to-board connector for electrically connecting two circuit boards.
2. Description of the Related Art
Conventionally, as shown in FIGS. 28 to 38, there has been proposed a board-to-board connector comprising a male connector 901 and a female connector 1101 that can be fitted to the male connector 901 (see Japanese Laid-Open Patent Publication (Kokai) No. 2012-226977).
The male connector 901 is mounted on a first circuit board 991 (see FIGS. 36 and 37). As shown in FIG. 28, the male connector 901 includes a base film 915 having insulating properties, conductor traces 951 provided on one surface of the base film 915, and a reinforcing layer 916 provided on the other surface of the base film 915. The base film 915 is formed of resin, such as polyimide, and the reinforcing layer 916 is formed of metal, such as stainless steel.
The conductor traces 951 are formed by patterning a copper foil affixed to the one surface of the base film 915 by performing etching thereon. The conductor traces 951 are arranged at a predetermined pitch.
As shown in FIGS. 28 to 31, each conductor trace 951 includes a protruding terminal 953. The conductor trace 951 has a rectangular plate-like shape. The protruding terminal 953 has a cylindrical shape, and is circular in cross-sectional shape (see FIGS. 30 and 31). The protruding terminal 953 protrudes from a surface of the conductor trace 951. The protruding terminal 953 is integrally formed with the conductor trace 951 by etching using a photolithography technique or the like method.
A pair of sides of the base film 951, extending along a longitudinal direction D, are each formed into a comb-like shape such that recesses 915A and protrusions 915B are alternately arranged (see FIG. 28). The recesses 915A and the conductor traces 951 positionally correspond to each other. Therefore, part of each conductor trace 951 is exposed on a mounting surface 901A of the male connector 901 (see FIG. 29). Each exposed portion (tale portion 958) of each conductor trace 951 is soldered to a connection pad (not shown) of the first circuit board 991 shown in FIGS. 36 and 37.
The female connector 1101 is plate-shaped (see FIGS. 33 and 34), and is mounted on a second circuit board 1191 (see FIGS. 36 and 37). The female connector 1101 includes frame bodies 1111. Each frame body 1111 is a plate-shaped member having a layer structure in which a cover film 1117 and a frame reinforcing layer 1116 formed by a pair of reinforcing layers are laminated in the mentioned order on conductor traces 1150, described hereinafter (see FIG. 32). The cover film 1117 is an insulating thin plate member and is formed of resin, such as polyimide. The frame reinforcing layer 1116 is formed of metal, such as stainless steel. The pair of reinforcing layers of the frame reinforcing layer 1116 are referred to as the first reinforcing layer 1116A and the second reinforcing layer 1116B.
Part surrounded by the frame bodies 1111 forms a connection recess 1114 (see FIG. 33) for accommodating part of a main body 911 of the male connector 901 except main body end portions 911C (see FIGS. 29 and 30). As shown in FIGS. 32 to 34, a bottom portion 1114A of the connection recess 1114 is a plate-shaped member having a layer structure in which a reinforcing layer 1118, a base film 1115, and the conductor traces 1150 are laminated in the mentioned order starting from the side of a mounting surface 1101A. The conductor traces 1150 are arranged on one surface of the base film 1115, and the reinforcing layer 1118 is arranged on the other surface of the same. The material and manufacturing method used for forming the conductor traces 1150 and the reinforcing layer 1118 are the same as those for the conductor traces 951 and the reinforcing layer 916 of the male connector 901.
The conductor traces 1150 include female conductors 1151 and auxiliary conductors 1152. The female conductors 1151 are arranged at equally-spaced intervals. Four of the plurality of arranged female conductors 1151 are replaced by the auxiliary conductors 1152, respectively.
Each female conductor 1151 includes a reception terminal 1153 (see FIG. 33). The reception terminal 1153 is accommodated in a terminal accommodating opening 1154. As shown in FIG. 35, the reception terminal 1153 includes a main arm portion 1153A, an auxiliary arm portion 1153B, and a protruding portion 1153C.
Each auxiliary conductor 1152 includes a holding portion 1157 (see FIGS. 33 and 35). The holding portion 1157 is accommodated in a holding portion-accommodating opening 1159. The holding portion 1157 includes base portions 1157A, first arm portions 1157B, second arm portions 1157D, and protruding portions 1157C.
To fit the male connector 901 and the female connector 1101, as shown in FIGS. 36 and 37, first, in a state in which a fitting surface 901B (see FIG. 31) of the male connector 901 and a fitting surface 1101B (see FIG. 33) of the female connector 1101 are opposed to each other, the male connector 901 is moved down to the female connector 1101 as indicated by an arrow B in FIG. 36, and part of the main body 911 of the male connector 901 except the main body end portions 911C is accommodated in the connection recess 1114. At this time, the protruding terminals 953 are each inserted into a main inner opening 1154A1 inside the main arm portion 1153A, which is inside the reception terminal 1153, and a first inner opening 1159A1 inside the holding portion 1157, which is located between the first arm portions 1157B (see FIG. 35).
Next, the male connector 901 is slid in a locking direction C (see FIG. 37) relative to the female connector 1101. When the male connector 901 has been slid, the protruding terminals 953 are each enter a positioning opening 1154C inside the reception terminal 1153, and a second inner opening 1159A2 inside the holding portion 1157 (see FIGS. 35 and 38). As a result, spacing between a contact portion 1153A3 of the reception terminal 1153, a contact portion 1153B3 of the auxiliary arm portion 1153B, and the protruding portion 1153C is widened by side portions of the protruding terminal 953. Then, by action of returning forces of the main arm portion 1153A and the auxiliary arm portion 1153B, the contact portion 1153A3 of the main arm portion 1153A, the contact portion 1153B3 of the auxiliary arm portion 1153B, and the protruding portion 1153C are in a state pressed against the side portions of the protruding terminal 953. That is, the contact portion 1153A3 of the main arm portion 1153A, the contact portion 1153B3 of the auxiliary arm portion 1153B, and the protruding portion 1153C hold the side portions of the protruding terminal 953 by the returning forces thereof. Thus, the protruding terminal 953 and the reception terminal 1153 are positively brought into contact with each other to attain electrical conduction.
However, since the plate-shaped conductor traces 951 of the male connector 901 are provided on the one surface of the base film 915, and the cylindrical protruding terminals 953 protrude from the surfaces of the conductor traces 951, after the part of the main body 911 of the male connector 901 except the main body end portions 911C is accommodated in the connection recess 1114, if the male connector 901 is erroneously slid in the longitudinal direction D of the connector (see FIG. 28) relative to the female connector 1101, each conductor trace 951 of the male connector 901 may short-circuit adjacent ones of the female conductors 1151. To avoid this short-circuit, it is only necessary to increase spacing between each adjacent pair of conductor traces 951 of the male connector 901 or increase spacing between the conductor traces 951 and the female conductors 1151 in the fitting direction, but this increases the size of the board-to-board connector.